Hannah is a 19-year-old college sophomore who came to Student Health with a chief complaint of lower abdominal pain

Hannah is a 19-year-old college sophomore who came to Student Health with a chief complaint of lower abdominal pain. She says the pain has been present for 2 months and she has had multiple episodes of diarrhea alternating with constipation, and anorexia. She says she has lost about 10 pounds in these 2 months without dieting. The abdominal pain has gotten worse in the last 2 hours, but she thought she had “the GI bug” like other students at her Synagogue had.

Physical exam-noncontributory except for the abdomen which was lightly distended with no visible masses. Normoactive BS x 4. Diffuse tenderness throughout but increased pain on deep palpation LUQ & LLQ. Slight guarding but no rebound tenderness or rigidity.

Rectal-tight anal sphincter and patient grimacing in pain during exam. Slightly + guaiac stool.

Based on her history and current symptoms, the APN arranges for a consult with a gastroenterologist who diagnoses Hannah with ulcerative colitis (UC).

Question:

How does ulcerative colitis develop in a susceptible person?